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Does Axion Dark Matter Exist?

Dark-matter axion research spearheaded by Berkeley Physics Professors Dmitry Budker and Surjeet Rajendran is one of two new grants recently announced by The Heising-Simons Foundation.

The Foundation will fund a team consisting of researchers from UC Berkeley, Stanford and the University of Mainz who are developing an entirely new search strategy for axions of much lower mass – down to a trillionth of an electron-volt. Dubbed the Cosmic Axion Spin-Precession Experiment (CASPEr), this project employs very sensitive nuclear magnetic resonance (NMR) technology to observe an effect predicted by theory, that the ubiquitous axion field would affect nuclear spins. Dmitry Budker and Surjeet Rajendran, UC Berkeley professors of physics, lead the effort and anticipate that the Heising-Simons funding will allow them to begin constructing the apparatus in 2016.

In the second grant, UC Berkeley, Yale, Colorado and Lawrence Livermore National Laboratory are seeking to detect axions inside a microwave cavity within a strong magnetic field as they convert to photons. The Berkeley effort is led by Karl van Bibber, professor of nuclear engineering, and focuses on making thin-film superconducting microwave cavities that will boost the axion conversion rate. Called the Axion Dark Matter eXperiment - High Frequency (ADMX-HF), this project will pave the way for searches at high axion mass, and serve as an innovation test-bed for developing new technologies to improve the sensitivity of larger experiments, in particular the ADMX platform at the University of Washington. As part of the same project, the researchers will try to improve the sensitivity of ADMX-HF by developing a microwave amplifier that evades the theoretical lower limit on noise set by quantum mechanics.

"The Heising-Simons funding goes beyond simply supporting research in this emerging new sector of dark-matter science," van Bibber said. "It strategically establishes a collaborative network for the whole national program in search of axions. We want the axion to be discovered here in the United States, and that will require a well-coordinated effort among many institutions."